8 February 2007, Rome - Cats can become infected with the highly lethal H5N1 avian influenza virus, but at present there is no scientific evidence to suggest that there has been sustained transmission of the virus in cats or from cats to humans, FAO said in a statement today.

As a precautionary measure, FAO recommended that in areas where the H5N1 virus has been found in poultry or wild birds, cats should be separated from infected birds until the danger has passed. On commercial poultry premises cats should even be kept indoors.

The agency advised against killing cats as a virus control option because there is nothing to suggest that cats are transmitting the virus in a sustained way. Removing cats could lead to a surge in rodents such as rats, which are an agricultural pest and often transmit diseases to humans.

Unconfirmed reports that H5N1 infection has been detected in a high prevalence in cats in Indonesia has caused some alarm. The scavenging cats were sampled in the vicinity of poultry markets in Java and Sumatra where outbreaks of H5N1 avian influenza had recently occurred.

This is not the first time that cats have been infected as previous incidents in Thailand, Iraq, the Russian Federation, the European Union and Turkey show. Cats can become infected by feeding on sick domestic or wild birds; they can develop severe to fatal disease and excrete the virus from the respiratory and digestive tracts.

“This raises some concern not only because cats could act as intermediary hosts in the spread of the H5N1 virus between species but also because growth in cats might help the H5N1 virus to adapt into a more highly infectious strain that could spark an influenza pandemic,” said FAO Assistant Director-General Alexander Müller.

“Findings reported from Indonesia in January, however, suggest that around 80 percent of cats in outbreak areas have not been infected. This is rather encouraging because it indicates that cats are unlikely to constitute a reservoir of virus infection. Cats are more likely to be a dead-end host for the H5N1 virus,” said Peter Roeder, FAO Animal Health Officer.

FAO said that cats should be closely monitored for any H5N1 infection. “Any unusual mortality in cats should spark a suspicion of H5N1. Infection in cats could be an early warning signal for the virus. The observation of cats should therefore become part of surveillance systems in affected areas,” Roeder said.

FAO will start field studies in areas in Java where the H5N1 virus is prevalent and where cats have died to investigate their role in disease transmission. This research will be extended to other parts of Indonesia and elsewhere. “We also need experimental studies to better understand the biology of H5N1 infection in cats, including most importantly the duration of virus shedding by infected animals,” Roeder said.

8 February 2007 - Cats can become infected with the highly lethal H5N1 avian influenza virus, but at present there is no scientific evidence to suggest that there has been sustained transmission of the virus in cats or from cats to humans.